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Many of us would define rheumatism as a disease of ache in the bones, pain and swelling in the joints, difficulty in moving or performing manual activities. Meanwhile, according to modern medicine, such a disease does not exist, but one rheumatism has replaced the entire spectrum of rheumatic diseases, plaguing every fourth Pole! By examining the blood, they can be detected and differentiated from other, similarly manifested diseases.
Generalized diseases of connective tissue
Today’s rheumatologist is primarily concerned with generalized connective tissue disease (CTD). They include those that lead mainly to bone and joint dysfunction (along with disability), but also those that attack the skin, kidneys, lungs, heart, blood vessels and the nervous system. The CTD includes, among others rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), polymyositis (PM), mixed connective tissue disease (MCTD) or Sjögren’s syndrome (SS).
These diseases are caused by autoimmunity – an attack of the immune system on its own tissues. This attack is associated with inflammation, manifested by pain, swelling, redness, warming, and impairment of the function of a given organ or tissue.
How to confirm the inflammatory nature of the disease?
Inflammation is also confirmed by blood tests. Increased level of the so-called inflammatory markers may be the first sign of rheumatological diseases, and it also helps to distinguish between inflammatory and degenerative diseases of the musculoskeletal system, which is important in choosing the right treatment. Moreover, these markings allow to track the dynamics of the ongoing disease – changes in their values correspond to changes in the severity of the disease. The most popular markers of inflammation are ESR and CRP. Both of these indicators are nonspecific – an increase in these indicators means that there is inflammation in the body, but gives no information about its source. It can be both rheumatic disease and a minor infection; cancer and caries. It is therefore important to diagnose rheumatic diseases when other possible causes are eliminated.
At Medonet Market you can buy a package of tests that will allow you to determine whether the causes of health problems, e.g. stiffness of the limbs, are rheumatological problems.
Autoantibodies in generalized diseases of connective tissue
So how do you know if your symptoms are caused by CTD? The laboratory can check whether the blood contains autoantibodies specific to specific connective tissue diseases. These particles recognize different cell structures, which we describe as an antibody against- or anti- (abbreviated a-) of a given structure. Both their presence and their absence make it easier for the doctor to make a diagnosis.
The “counterpart” of old rheumatism may be RA. Autoantibody confirming its diagnosis is the so-called rheumatoid factor (RF). In the past, it was detected in the blood mainly in agglutination tests – as a Waaler-Rose or latex test. More accurate immunochemical methods are now available, also allowing quantification of RF quantitatively. It is also helpful to test anti-CCP antibodies (autoantibodies to cyclic citrullinated peptide), which appear in the blood even before the symptoms of RA, and therefore can predict the appearance of the disease. These indicators allow the differentiation between RA and degenerative joint disease in which ESR and CRP may be normal or slightly elevated, while RF and anti-CCP are absent.
Laboratory diagnosis of other generalized connective tissue diseases is based on the determination of antinuclear autoantibodies – PPJ (ANA). There are several dozen types of these antibodies that recognize various structures within the nucleus or cytoplasm of cells. In different diseases, ANAs come in different combinations. Each disease has its own specific antibodies, the presence of which is a high probability of a given disease. The same antibody, however, may also appear less frequently in other disease entities, accompanying another type of ANA. This phenomenon is also observed in the so-called overlapping syndromes, i.e. the coexistence of at least two different diseases. Efficient diagnostics of connective tissue diseases is facilitated by a step-by-step procedure. In the laboratories of the “Diagnostyka” network, the first step is a qualitative screening test of PPJ – ANA1. Its result only tells you if there are any ANA-type antibodies in your blood. If so, the PPJ – ANA2 comprehensive test can be performed from the same sample. ANA2 allows not only to determine the type of autoantibodies (there may be several of them) but also their amount (titer), which in some diseases is important in prognosis. For the identification of some rarer autoantibodies or the need for more detailed determinations (e.g. distinguishing between two subunits of the Ro antibody), it is necessary to order the ANA3 panel. It is also possible to perform detailed tests revealing one specific antibody (eg against ANuA nucleosomes in differentiating between SLE and SSc) or, conversely, to determine a “set” of antibodies specific to a given disease (eg panel scleroderma in systemic sclerosis). In the diagnosis of SLE, besides ANA, the determination of anti-cardiolipin and anti-β2 glycoprotein antibodies is also useful. The combinations of the most important autoantibodies in some generalized connective tissue diseases are presented in the table.
Ankylosing spondylitis
Coming back to the symptoms signaled at the beginning, one should also mention ankylosing spondylitis (AS). This disease most often occurs in men around the age of 30-40, causing pain in the lower spine and its morning stiffness. It can lead to disability. It is an inflammatory disease of the joints, but unlike RA, no RF or anti-CCP is detected in the patient’s blood. 90% of AS patients have the HLA-B27 antigen. Its presence is genetically determined – this antigen does not appear in the course of the disease, but is a permanent feature of a person. This means that the presence of HLA-B27 may predispose to AS, and in combination with characteristic symptoms it may constitute a diagnosis of the disease. The mere possession of HLA-B27, however, is not a “death sentence” – the disease occurs with the coexistence of environmental, infectious or immunocompromised factors.
Other diseases causing rheumatic symptoms
In addition to inflammatory diseases and degenerative processes related to physical stress or age, biochemical disorders can cause bone and joint pain. One of the best known is gout, in which we observe an increase in the concentration of uric acid in the blood. Some infections can also cause “rheumatic” ailments. In the “Diagnostyka” laboratories, a panel test can be performed to detect the most common of them (such as Varicella, Influenza A H1N1, Influenza A H3N3, Influenza B, Yersinia, Toxoplasma, Borrelia afzelii, Borrelia burgdorferii, Borrelia garinii, Chlamydia).